TYPES of BONESBones are essential to human survival.
In addition to protecting the organs, they give the body shape and structure—kind of like the framework of a house. Without the skeleton, movement wouldn’t be possible.
2
SKELETAL SYSTEM
There are two divisions of the skeletal system: the axial skeleton and the appendicular skeleton.
axial skeleton
appendicular skeleton
3
AXIAL SKELETON
head
trunk
vertebral column
The axial skeleton is made up of the bones of the head (skull), trunk (rib cage and sternum), and vertebral column. In total, the axial skeleton contains 80 bones.
4
APPENDICULAR SKELETON
The appendicular skeleton is made up of the bones of the upper and lower extremities, as well as the bones that form the shoulder and hip girdles, which connect the limbs to the axial skeleton. In total, there are 126 bones in the appendicular skeleton.
5
FIVE TYPES OF BONES
Five types of bones make up the skeleton: long bones, short bones, flat bones, sesamoid bones, and irregular bones.
long bone (humerus)
short bone (carpals)
flat bone (sternum)
irregular bone (maxilla)
sesamoid bone (patella)
6
Long bones have a long length and a smaller width. These bones consist of a shaft and a variable number of extremities. Long bones are responsible for absorbing the stress of the body’s weight at several different points.
LONG BONES
7
LONG BONES
Long bones vary greatly in size. Examples of long bones include the femur, radius, and even the phalanges.
femurradius
phalanges
8
Short bones are more or less cube-shaped with very similar lengths and widths. Most of the carpal and tarsal bones are short bones.
SHORT BONEStarsal bones
carpal bones
9
FLAT BONES
Flat bones are generally thin and are responsible for giving protection and area for muscle attachment. Examples of flat bones include the cranium, sternum, and the ribs.
parietalfrontal
nasal
lacrimal
occipital
10
SESAMOID BONES
Fun fact: The word “sesamoid” comes from the Latin “sesamum,” meaning “sesame seed.”
Sesamoid bones are embedded in tendons. The most notable example of a sesamoid bone is the patella. Sesamoid bones vary in number from person to person, and are typically only a few millimeters in size.
patella
quadriceps femoris
11
IRREGULAR BONES
Irregular bones cannot be grouped into any other categories because of their complex shapes. Examples of irregular bones include vertebrae, hip bones, and certain facial bones, like the maxillae or zygoma.
zygomatic bone
12
SKULL
The skull is made up of 22 bones and is part of the axial skeleton. The bones in the skull are divided into two categories: the cranial bones (which form the cranial cavity) and the facial bones (which form the face).facial bones
cranial bones
13
VERTEBRAL COLUMN
Fun Fact: The vertebral column makes up about 2/5 of your entire height.
The vertebral column is made up of 33 bones: 24 presacral bones, 5 fused bones of the sacrum, and 4 fused bones of the coccyx. Along with the sternum and ribs, the vertebral column forms the trunk of the body, protects the spinal cord, supports the head, and serves as an attachment point for many other bones and muscles.
14
VERTEBRAL COLUMNCONT’D.
The presacral vertebral column is categorized by the location of the vertebrae:
• Cervical vertebrae are in the head/neck region
• Thoracic vertebrae are in the thoracic region (think thoracic cage)
• Lumbar vertebrae are in the lumbar region (lower abdomen)
cervical vertebrae
lumbar vertebrae
thoracic vertebrae
15
SACRUM
Fun Fact: The word “sacrum” comes from the Latin “os sacrum” or “sacred bone.” The bone was considered sacred because it was often the part of an animal that was offered in sacrifices.
The sacrum is comprised of five bones that fuse during childhood. In a female skeleton, the sacrum is shorter and wider than in the male, and it is directed more obliquely backward, increasing the size of the pelvic cavity.
female sacrummale sacrum
16
COCCYX
The coccyx is the terminal portion of the vertebral column and forms part of the posterior wall of the pelvic cavity. It resembles a miniature sacrum in shape.
Fun Fact: The word “coccyx” comes from the Greek “kokkyx,” meaning “cuckoo,” for its resemblance to the bill of the cuckoo bird.
coccyx
sacrum
lumbar vertebrae
A universe of anatomical and physiological visuals and reference texts at your fingertips!
www.visiblebody.com
View a 3D Tour of all the images featured in this eBook!
If you have a mobile version of Human Anatomy Atlas 2021.1 or later: 1. Click here to view the tour.
If you have a web version of Atlas:1. Copy this link:
https://apps.visiblebody.com/share/?p=vbhaa&t=4_27073_637522012260383710_200455
2. Use the share link button in the app.3. Paste the link to view the tour.
